DELLA Proteins in Signalling

Abstract

DELLA proteins have emerged as important modulators of prewired transcriptional circuits in response to the environment. In vascular plants, proteasome‐dependent degradation of DELLAs is induced by gibberellins, whose levels are strongly regulated by environmental signals such as light, temperature and nutrient availability. Transcriptional regulation is exerted by DELLAs through physical interaction with DNA‐binding transcription factors and other transcriptional regulators. The key biological role of DELLAs has been proposed to regulate the balance between growth and stress responses, which justifies the inadvertent selection of hyperstable DELLA alleles during the breeding programs that lead to the Green Revolution. DELLA proteins are also present in nonvascular plants which do not synthesise active gibberellins, suggesting that the origin of DELLAs predates the emergence of gibberellin biosynthesis. Key Concepts DELLAs are nuclear proteins that modulate the activity of a large set of transcription factors through protein–protein interaction. DELLA protein degradation is regulated by environmental signals mostly through gibberellin signalling. DELLA proteins are ‘hubs’ that control the balance between growth and stress responses. The origin of DELLA proteins predates the appearance of bioactive gibberellins. Manipulation of DELLA proteins has contributed to the ‘Green Revolution’.